The photograph above isn't a fake. This is a real creature known as Bathynomus giganteus, or the Giant isopod. Although it looks like a fantasy creature from a sci-fi film, this is actually a genuine organism that lives in the depths of the Atlantic and Pacific Oceans and was first discovered off the Gulf of Mexico in 1879.

It's believed to be a scavenger that feeds upon dead whales and squid in the pitch black darkness of the bathypelagic zone, some 2140m/7020ft below the water surface.

If you fancy seeing them for real, some giant ispods went on display at the Sea Life Centre at Blackpool for the first time in Britain last year.

It's quite grotesque to look at, but it's not nearly as disgusting as some of its other cousins in the Order Isopoda.

Take the Tongue-eating louse, Cymothoa exigua, for example.

This member of the isopod family Cymothoidae (pictured above) is a parasite and attaches itself to the tongue of fishes, usually snappers, holds on with its claws and drinks blood from the artery that lies within the tongue.

Eventually, the tongue withers away due to the reduced blood supply, but the parasite remains, turning into a replacement tongue that the fish can use as normal (see picture below) – in return for a share of each meal consumed.

Ian tells us: "The parasite measured 7mm across by 8.5mm long and was tucked away inside a Corydoras gracilis, which was just 30 mm in length." Pictures courtesy Dr Peter Burgess.

Now, it seems, they're going for the genitals. At least, sort of. In a round about kind of way. A team of scientists from Brazil has studied parasitism by another cymothoid parasite called Riggia paranensis, which apparently exhibits something known as "parasitic castration". See Fish parasite castrates its host.

This is an item from the Practical Fishkeeping archives and was first published in 2007.